Hokkaido's flagship onsen ryokan: a vast 5,000 m² bathhouse overlooking Jigokudani with 35 tubs fed by five spring types — sulfur, salt, sulfate and more. Day bathing is accepted from 9:00 to 18:00. An indoor heated pool makes it good for families. Tattoos not permitted.
The only bathhouse-style onsen in the middle of Noboribetsu's resort strip. Two spring sources piped from Jigokudani — sulfur and the alum 'eye bath' found nowhere else — for ¥500.
In the Hakkoda mountains, bathing since 1684 and Japan's first National Recuperation Onsen. A vast all-cypress mixed bath hall (about 260 m²) fed by four sources. Women-only hour 8–9 am daily; bathing garments sold on site.
A communal bath with over a thousand years of history as the shrine's sacred spring. Milky acidic sulfur water pours like a waterfall from log flumes into cypress tubs. ¥300; bring your own soap.
A terraced open-air bath along a mountain stream that holds 200 people, with bluish-white strongly acidic sulfur water. Open late April to late November only; closed in winter. Summer starlight sessions at night.
At 1,800 m, one of Japan's highest onsen. Milky water with some of the country's highest sulfur content, across nine tubs. Day use 10:00–17:00; prices rise in peak season.
A milky open-air bath on a hillside above Beppu Bay. Thatched 'yunohana huts' where bath salts are harvested — a national cultural property — line the grounds and can be visited free. Hell-steamed food too.
A vast garden bath hall fed by 14 sources at 1,400 litres a minute, with four water types — sulfur, alum, saline and iron — in one place. The central pool is mixed-gender (women-only hours; bathing garments allowed).
A free foot bath in an actual river of hot spring water flowing out of Ōyunuma pond, at the end of a forest boardwalk. The perfect finish to a Jigokudani walk. Daylight hours; the trail may close in deep snow.
The 1,300-year-old birthplace of Nasu Onsen. Inside the wooden bathhouse, tubs are graded from 41 to 48°C, all fed with milky, strongly acidic sulfur water. No showers, no soap — start with the traditional head-dousing ritual.
A day-use facility on the same source as Shika-no-yu, open every day until 9 pm with an open-air bath and private rooms. Ideal for families or anyone daunted by Shika-no-yu's rituals — the milky water is identical.
A historic cure-bath in the hills a short way from Unzen's main street, said to have hosted Siebold and Yoshida Shōin. An octagonal wooden bathhouse with milky sulfur water cooled from a 90°C source. No open-air bath, but Unzen's finest water.
The innermost of Nyūtō's seven baths — a cluster of thatched bath huts. Two separate sources feed a mixed open-air pool and gender-separated indoor/outdoor baths of milky sulfur water. Day use 9 am–4 pm, the longest window of the seven; closed mid-November to mid-April.
A day-bath with a simple lodging near the entrance to Unzen Jigoku. Every tub is free-flowing milky sulfur water — indoor, open-air and four private outdoor baths. ¥500, 9 am to 9 pm; an easy stop before or after touring the 'hells'.
A log-cabin-style communal bath at the top of Takayu-dōri. Zao's three public baths (Kamiyu, Shimoyu, Kawarayu) all cost ¥200, paid into an honesty box. No washing stations — just rinse and sink into the strongly acidic milky sulfur water.
In Nozawa, where 13 outer baths are free (donation), this is the only paid day facility with showers, shampoo and an open-air bath. A handsome building with a curved gable, hot and mild indoor pools and a stone outdoor bath — the fallback when the outer baths are too hot or you want a proper wash.
At 1,800 m in Manza, four private sources feed eight open-air pools of milky, yellow and clear water — the famous 'Sekitei' rock-garden baths. Mixed bathing, but gowns or wrapped towels are required and there is a women-only pool. Day use 11 am–6 pm (last 5 pm), ¥1,700.
Forty minutes by car from Niigata city, the communal bath of Tsukioka Onsen, which bills itself as the spring that 'makes you beautiful'. The emerald-green water has one of the highest sulfur contents in Japan — you smell it the moment you step in. Indoor pool only, ¥600. On the edge of the ryokan street and popular with locals. 25 minutes by bus from Shibata Station. Closed Tuesdays and the third Wednesday.
A small riverside hotel on the south side of Kinugawa Onsen, five minutes from Tobu World Square Station. While the big hotels stop day bathing around 15:00, this one welcomes walk-ins 9:00–21:00 for ¥700. Its own alkaline sulfur spring (43.6 °C) flows 100% free into a quirky set of baths: a rotenburo made from an actual Kinugawa river-cruise boat, a rock rotenburo, indoor baths and a swimsuit mixed bath. The slightly cool, silky water is highly rated by onsen fans.
The village-run public bath of Tōsenji Onsen, the oldest spring in Totsukawa. pH 9.1 alkaline sulfur water flows fresh from the source even through the taps, leaving a faint sulfur scent and slippery skin. Just a stone open-air bath facing the gorge and an indoor tub—simple and ¥600. Handy on Route 168 en route to the Tanize suspension bridge or Kumano Hongū Taisha.
The only hot spring inscribed as a World Heritage Site that you can actually bathe in, listed together with the Kumano Kodo pilgrimage routes. A tiny hut over the stream in Yunomine — said to be Japan's oldest onsen at 1,800 years — shelters a tub hollowed from natural rock that fits two adults. The sulfurous water is said to change colour seven times a day and served pilgrims for ritual purification. Private 30-minute slots, ¥800, sign up at the public bathhouse (6:00–21:00). Waits of several hours are common on holidays; boil onsen eggs in the hot-spring trough while you wait.
The flagship hotel of Manza Onsen, which at 1,800 m is among the highest hot-spring resorts in Japan reachable by car all year. Perched on a rise, its famous 'Komakusa-no-yu' open-air bath juts from the mountainside so you soak in milky sulphur water while gazing at a sea of clouds, the Jōshin'etsu ranges and, in winter, unbroken snow — literally a bath above the clouds. Besides separate men's and women's sections there is a mixed zone where a wrap towel is worn, making this one of the few Manza inns where mixed bathing is possible. The sulphur content is among Japan's highest and the scent lingers after. Day bathing: adults ¥1,500, children ¥750, reception 11:00–16:00 (bath entry until 15:00), face towel included (bath towel hire ¥300). Weekdays are far quieter than weekends. About 2 hours by Seibu bus from Karuizawa Station, or about 40 minutes by bus from Manza-Kazawaguchi Station; direct ski-slope access in winter.
Because drilling is banned inside the national park, every bath in Unzen runs on naturally rising water. This little communal bath on the edge of the spa town, known locally as 'Dankyū-buro', has just one deep oval pool into which the acidic hydrogen-sulphide spring flows fresh; depending on the season and the day it may be milky white or nearly clear. It is hot, 43–44°C, with a faint sulphur scent. Adults ¥200, children ¥100; open 09:00–22:00, closed Tuesdays. No dryers or amenities — soap is sold — but there are lockers, and parking for four cars. After touring the Unzen Hells, a rare chance to taste the local bath for ¥200, a world apart from the big tourist bathhouses.
The highest hot-spring inn in Tōhoku, at 1,400 m near the top of the Hachimantai Aspite Line. It opens only from Golden Week to late October; in winter it is buried in snow. Five mixed open-air baths scattered down the slope (plus a women-only open-air bath and separate indoor baths) are fed by sulphur water bubbling up directly through the ground, milky white, and the trademark is smearing the mud from the bottom on your skin as a 'mud pack'. Below spread Mt Iwate and a sea of forest; at dawn, cloud seas and sunrise — truly a bath above the clouds. Simple sulphur water at temperatures from tepid to hot. Day bathing: adults ¥650, children ¥350, with a long 08:00–18:00 window, busy with hikers back from the Hachimantai summit trail. The open-air baths are mixed, so bathing garments and wrap towels are allowed. About 2 hours by bus from Morioka Station or 40 minutes by car from Matsuo-Hachimantai IC. Mobile reception is poor.
The representative drop-in bath of the Mizusawa spa cluster on the Tazawako plateau, on the road up to Nyūtō Onsen. Less famous than Nyūtō's hidden inns, it nonetheless runs an abundant sulphur-calcium-magnesium-sulphate-chloride spring free-flowing, and its bluish milky water is praised as 'silky and moisturising'. The standout is an open-air bath about a metre deep in which you soak standing up — one of only two such deep outdoor baths in the area. Men and women each have two indoor and two outdoor baths, and the waterfall massage runs all the time. Adults ¥900, primary-school children and under free; open 10:00–20:00 (building closes 21:00), irregular closures (open through Golden Week, Obon and New Year). Lodging is available, and it makes a good alternative when Nyūtō is crowded or a stop after Tazawako ski slopes or a climb of Mt Akita-Komagatake. About 25 minutes by Ugo Kōtsū bus for Nyūtō Onsen from JR Tazawako Station to 'Mizusawa Onsenkyō', right by the stop; 60 parking spaces.
A mainly day-use hot-spring house at Senami Onsen in Murakami, Niigata, famous for sunsets over the Sea of Japan. Its own source 180 m down yields abundant water at about 94 °C, and although it is a seaside spa the water has a faint whiff of sulphur and leaves the skin silky. There is an indoor bath, a rugged rock-built outdoor bath and a mist sauna, and even the showers run spring water; in winter the outdoor bath becomes a snow-viewing bath. Private family baths, rentable rooms, weekday day plans with a meal (from ¥4,800) and overnight stays are also available. Adults ¥900, children ¥500, towel hire ¥210; open 09:00–22:00 (last entry 21:00), irregular closures. About 10 minutes by bus from JR Murakami Station or 12 minutes by car from Murakami-Senami-Onsen IC; 100 parking spaces. Combine with Murakami's salmon cuisine, its merchant townhouses and a sunset walk on Senami beach.
The public bath at the heart of Yunomine Onsen, one of Japan's oldest springs, where pilgrims purified themselves before Kumano Hongū Taisha. The building, renovated in 2022, also serves as reception for the World Heritage 'Tsuboyu'. There are three bathrooms: the 'Ippan-yu' with hot and tepid tubs (adults ¥400, shampoo provided), the concentrated 'Kusuri-yu' filled with undiluted source water (¥600, no soap allowed) and a 30-minute private family bath (¥700), all sulphur-scented sodium-bicarbonate-chloride water ranging from milky to clear. Tsuboyu (¥800, 30-minute slots) can mean a wait of hours when busy, so the clever order is to take a number and warm up in the public bath first. Open 06:00–21:00 (last entry 20:30), irregular cleaning closures. The village also has the 'Yuzutsu', a 90 °C source where you boil eggs and vegetables, and is the trailhead of the Dainichi-goe section of the Kumano Kodō. About 2 hours by bus from JR Kii-Tanabe or Shingū stations to 'Yunomine Onsen', right by the stop; 46 parking spaces.
A town-run hot spring inn on the clear Katsuura River in Kamikatsu, Tokushima – the village famous for its 'leaf business' and zero-waste pledge – that welcomes day bathers. The simple sulfur cold spring is heated for the baths and has a faint sulfur scent and a slippery, smoothing feel. The open-air bath faces the stream and looks over fresh greenery, autumn colour and terraced rice fields, with an indoor bath and sauna alongside. Adults (junior-high and up) pay ¥650 and children from 3 to elementary age ¥350; open 10:00–20:00, closed the second Wednesday. The dining room serves Kamikatsu mountain vegetables, Awa-odori chicken and dishes garnished with the village's celebrated 'irodori' leaves, and stays combining the adjacent campground and Kamikatsu tea farms are popular. Free parking for 150 cars, coaches welcome. About 50 minutes (39 km) by car from central Tokushima or 80 minutes from Tokushima IC; by Tokushima Bus on the Kamikatsu line to the Tsukigatani Onsen stop near the terminus. Pair it with the Kashihara rice terraces and the RISE & WIN brewery.
A day bath inside Alpa Komakusa, the Semboku city complex where buses depart for the 8th station of Mt. Akita-Komagatake. Sharing the building with the mountain information centre and volcano disaster station, it bustles with hikers and Lake Tazawa sightseers. The 'Nature Onsen Hall' has two lookout open-air baths, one of rock and one of hiba cypress, gazing down on the lapis-blue surface of Lake Tazawa – Japan's deepest – and the sweep of the mountains. The milky simple sulfur spring rises from the same range as Nyūtō and Mizusawa onsen and warms a chilled body thoroughly with a soft sulfur scent. Admission is a modest ¥550 for adults and ¥300 for children. Hours are 9:00–19:00 (last entry 18:00) from April to November, 9:30–17:30 (last entry 17:00) from December to March, and 9:00–18:00 on Thursdays and Fridays; open daily except Thursdays from November to April. Rest corner and light meals available, with a large car park. From JR Tazawako Station take the Ugo Kōtsū bus bound for Nyūtō Onsen about 35 minutes to the Alpa Komakusa stop. Perfect for a soak on the way to or from Nyūtō or after climbing Komagatake.
A city-run day spa (Niigata City Iwamuro Health Promotion Centre) at Iwamuro Onsen, a spa at the eastern foot of Mt. Yahiko in Niigata's Nishikan ward, often called 'Niigata's back parlour'. Set on a rise at the edge of the spa town, its main bath and open-air bath look out over the Echigo plain toward Mt. Kakuda and Mt. Yahiko. The indoor pool is heated tap water, but the small rock-lined outdoor tub is fed with rich, free-flowing sulfur-bearing sodium-calcium chloride spring (hypertonic, mildly alkaline) whose faint sulfur scent and floating mineral flakes feel unmistakably like real onsen. Admission is ¥650 for adults and ¥390 for children, and a face and bath towel set is included, so arrive empty-handed. Open 10:00–20:00 (last entry 19:30), closed the second and fourth Wednesdays (next day if a holiday) and 29 December to 3 January. An upstairs lounge allows re-entry, and there are rental rooms and a snack corner; free parking for 80 cars. About 10 minutes by car from Iwamuro Station on the JR Echigo Line or 20 minutes from Maki-Katahigashi IC. Pair it with Yahiko Shrine and Niigata's sake breweries.